FSC 1st Year Physics Chapter 4 Short Questions Notes PDF

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In this post, I am sharing the FSC 1st Year Physics Chapter 4 Sort Questions Notes PDF for the students of Intermediate Part 1. This chapter’s name is Work and Energy. On ilmihub, 1st Year Physics book and all subject books are available to download in PDF format. From this post, students can download 11th Class Physics Chapter 4 Short Questions with Answers Notes in PDF format on their laptop or mobile. These class 11 Physics chapter 4 short questions notes are for all the boards working under the Punjab Board like Gujranwala Board, Lahore Board, Faisalabad Board, Multan Board, Rawalpindi Board, Sargodha Board, DG Kahn Board, and Sahiwal Board. From this link you can download the complete FSC 1st Year Physics Notes PDF chapterswise.

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FSC Part 1 Physics Chapter 4 Work and Energy Short Questions Notes PDF Download

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A person holds a bag of groceries while standing still, talking to a friend. A car is stationary with its engine running. From the standpoint of work, how are these two situations similar?

Case 1
The person is applying a force against gravity in holding the bag. As he is standing still and talking to a friend his displacement is zero in this case. So,

W = F.d

                                W = fdcosq
                                     = f(0) cosq = 0
Case 2
                In the case of a stationary car with its engine running, force is present but its displacement is zero. So,
                                W = F.d
                                W = fd cosq
                                     = f(0)cosq = 0
The two cases are similar because in both cases the work done is zero.

When a rocket re-enters the atmosphere, its nose cone becomes very hot. Where does this heat energy come from?

When a rocket re-enter the atmosphere, it has very high speed and works against air friction, the kinetic energy of the rocket is dissipated in the form of heat. So the nose cone of the rocket becomes very hot.

Define conservative and non-conservative forces.

Conservative Force:
A force that acts on a particle, such that the work done by this force in moving this particle from one point to another is independent of the path taken is called conservative force.
OR
The force due to which work done on the body along the closed path is zero is called conservative force.
Example;

Gravitational force
Electric force
Magnetic force

The fields produced by the conservative force are called conservative fields.

Non- conservative Force:

A Force that acts on a particle, such that the work done by this force in moving this particle from one point to another is dependent on the path taken is called a non-conservative force.

The force due to which work done on the body along the closed path is zero is called non-conservative force.

Example:

The frictional force is a non-conservative force. Work done against the frictional force depends upon the path followed.